The present invention relates to an insert coupling for connecting a flexible pipe section to another part.
Such an insert coupling is known in many embodiments. The disadvantage of such couplings is that they work in a manner that seals and clamps well only when pipes with a smooth surface are used. For the installation of Jacuzzis, use is made of flexible pipe sections with a spiral reinforcement provided therein, which means that, as a result of the spiral reinforcement, the outer surface of the pipe section is not smooth. In general, these types of pipe sections are glued, in order to obtain a good seal. The disadvantage of gluing the pipe sections is that the pipe section can no longer be rotated after the glue has hardened, which can make fitting in narrow spaces more difficult. Besides, the glue components can be polluting for the environment.
The object of the invention is to provide an insert coupling which overcomes the above mentioned disadvantages.
This object is achieved by an insert coupling for connecting a flexible pipe section to another part having therein a relatively hard spiral-shaped reinforcement, comprising a housing having therein a first cylindrical bore, which extends from an insertion side to a second cylindrical bore with a diameter which is smaller than the diameter of the first bore and which substantially corresponds to an external diameter of the flexible pipe section, so that a shoulder is produced as a boundary of the first bore. The insert coupling furthermore comprises a sealing ring, which rests against the shoulder in the first cylindrical bore and is effective between the flexible pipe section and the first cylindrical bore. The insert coupling also comprises a clamping bush, which is provided immovably in the axial direction in the first cylindrical bore and extends to the insertion side of the bore situated opposite the shoulder, the clamping bush having a cylindrical inner surface which in the region near the insertion side passes into a conical part that tapers towards the insertion side. Also, the insert coupling comprises a clamping ring accommodated in the clamping bush and having a supporting surface, which is situated on the inside, and which on the insertion side is provided with at least one radially inward projecting tooth, which has an end face that runs from the supporting surface substantially in the radial direction and a clearance face lying behind it and sloping outwards towards the insertion side, with an angle of inclination relative to the axial direction. The conical part on the inside surface of the clamping bush by way of the clamping ring causes a radially inward directed clamping force on the flexible pipe section when a load occurs on the flexible pipe section in the axial direction towards the insertion side, and in which the clamping ring is in the form of a ring cut through at one point substantially in the axial direction, from which clamping ring a cylindrical segment has been removed at the position of the cut.
The advantage of removing a cylindrical segment from the clamping ring is that, under the influence of the conical part of the clamping bush, the clamping ring can undergo a diameter reduction when a tensile force is exerted upon the pipe section in the direction of the insertion side, with the result that the clamping ring is clamped more firmly around the pipe section, but said clamping ring can still rotate along with the pipe section during the fitting operation, in order to be able to position the latter well in a certain space. In this design the clamping ring is also simple to manufacture.
In an advantageous embodiment the tooth height of the tooth on the clamping ring is dependent on the diameter of the flexible, reinforced pipe section. Preferably the tooth height is chosen 3% of the pipe diameter, so that the tooth engages well in the pipe material, but the pipe wall does not become so damaged that leakage occurs. For a good engagement the tooth shape is also important. In a preferred embodiment the end face is situated substantially perpendicular to the inside ring wall, and the clearance face is situated at an angle of approximately 45xc2x0 to the end face.
The conical part of the clamping bush is preferably oriented at an angle of approximately 30xc2x0 to the cylindrical inner surface, so that with a slight axial displacement of the pipe section in the direction of the insertion side a sufficiently great diameter reduction of the clamping ring is achieved to grip the pipe section in a clamped fit.
The invention will be explained in greater detail with reference to the drawings.